The invention belongs to the technical field of 
radar simulation, and particularly relates to a 
broadband radar coherent 
clutter simulation method based on DEM data. The 
broadband radar coherent 
clutter simulation method comprises the following steps that firstly, simulation parameters are loaded; secondly, data of a nth flight path point are read; thirdly, the radar platform position and the sum beam 
irradiation direction are determined; fourthly, the radar 
irradiation area is determined through an antenna pattern; fifthly, a ground scattering unit is divided in the 
azimuth direction and the pitching direction at intervals with dtheta and dphi serving as the pitching angle and the 
azimuth angle respectively, and the area of the scattering unit is calculated; sixthly, the 
voltage power and amplitude of an echo of the scattering unit are calculated according to the 
radar equation; seventhly, an echo 
voltage signal of the scattering unit is calculated according to the obtained 
clutter amplitude and the characteristics of an LFM 
signal; eighthly, the position of the echo of the scattering unit in radar echo data is calculated; ninthly, coherent combination is carried out on the echo 
voltage signal of the scattering unit; tenthly, whether n is smaller than N or not is judged, if yes, simulation is finished, or otherwise, the second step is repeatedly executed. Complex electromagnetic scattering calculation is not carried out under the situation that ground up and down changes are taken into consideration.